The Health Benefits of Garlic

There’s nothing like a little garlic to punch up a stir-fry, roast chicken, or pasta dish, but for centuries it has been purported to add some oomph to your health, too. Ancient civilizations used garlic to treat asthma, digestive disorders, heart disease, infections, respiratory disorders, tumors, and even intestinal worms. Today, claims for the health benefits of garlic include lower blood pressure and cholesterol, an anti-inflammatory effect, a reduced risk of cancer, and a stronger immune system.

While many of these claims are overblown, there is evidence of some health benefits. Here, on National Garlic Day, is what you should know about this pungent allium, and how to reap its benefits.

What Makes Garlic Special

Garlic’s pungent flavor comes from sulfur compounds made from allicin, an active ingredient once thought to be responsible for the health benefits of garlic. But according to Matthew Budoff, M.D., a professor of medicine at the Los Angeles Biomedical Research Institute who studies the effects of garlic on cardiovascular health, it has as many as 40 other compounds, and “any number or combination of them may be responsible for its healthfulness.”

Most of the studies on the health benefits of garlic used garlic supplements because they provide a consistent dose, though others used garlic powder, garlic oil, and a Japanese method of preparing garlic that involved kneading and pulverizing crushed garlic together with egg yolk. Budoff says the strongest evidence for the health claims suggests that garlic may help the heart, with data overall showing about a 10 percent reduction in cholesterol and a 3 to 8 point drop in blood pressure. “That isn’t quite as good as cholesterol or blood pressure pills," he says, "but it’s certainly a nice effect.”

In a small study of 55 people with metabolic syndrome—a group of risk factors, such as excess stomach fat or high blood pressure, that raise the risk of heart disease—published in the Journal of Nutrition, Budoff and his colleagues found that those who took a daily garlic supplement for a year had slower plaque buildup from coronary artery disease than those who took a placebo.

But many studies showing a cardiovascular benefit, though rigorous, are small, and not every study shows that garlic is beneficial. There has even been concern that garlic supplements may be harmful for some people with heart disease.

A research review published in the Journal of the American College of Cardiology found that garlic (along with green tea, ginkgo, ginseng, and hawthorn) can interfere with the efficacy of some heart medications or increase their side effects. For example, too much garlic can pose a bleeding risk for people on anticoagulants such as warfarin (Coumadin, Panwarfin) or a prescribed aspirin regimen. And according to the National Institutes of Health, it may also make some other drugs less effective, such as saquinavir, a drug used to treat HIV infection.

The authors of the Journal of the American College of Cardiology review also noted that garlic (and other herbal supplements) has “limited evidence of benefit,” meaning it might help but more research is needed.

The research is even weaker for garlic’s ability to fight bacteria, ward off colds, boost the immune system, or reduce the risk of certain cancers, such as stomach or colon cancer.

“There’s a lot of purported benefits of these medicines [garlic supplements],” Budoff says. “I’m more comfortable with the research on the cardiovascular benefits of garlic, and I’m less comfortable with it curing the common cold, acting as an antiviral, or other therapies.”

Garlic in Your Dinner

Perhaps for these reasons, experts say the best way to get your garlic is from the fresh clove, although there can be a few “side effects” from eating it fresh. Garlic breath is probably the worst of it, but some people do suffer from indigestion after eating fresh garlic. According to Budoff, garlic is an essential part of the Mediterranean diet, "which has been shown to have the best long-term outcomes of any diet we know of.” Studies have linked this way of eating—which emphasizes produce, legumes, grains, and healthy oils, with small amounts of fish and meat—to a better quality of life, a lower risk of chronic disease, and better brain health in older adults.

“I put garlic in everything,” says Maxine Siegel, R.D., a dietitian and head of Consumer Reports’ food-testing lab. “You can use it to spice up a healthy dish without having to add any salt. Just make sure to use fresh garlic instead of garlic salt, which will boost the sodium levels.”

How to Get the Most Out of Garlic

Choose the freshest bulbs. Look for plump bulbs with tight skin that isn’t frayed, loose, dried out, or moldy. Sprouting, too, is a sign of age. The fresher the garlic, the higher the concentration of its active ingredients, Budoff explains. Though garlic can keep for months, he says it’s best to eat it within a week. “If you go longer than that," he says, "you can end up with something that’s deactivated.”

Store it right. Keep garlic in a cool, dark place with good ventilation to prevent it from getting moldy or from sprouting.

Chop it for your health.Chopping, slicing, or smashing garlic triggers an enzyme reaction that increases its healthful compounds. Heat prevents this reaction, so let garlic sit on the cutting board for at least 10 minutes before cooking.

Minimize garlic breath. The smell of garlic can stay on your breath and be excreted by the lungs for a day or two after you eat it. A study published in the Journal of Food Science in 2016 suggests that munching on raw mint leaves, apples, or lettuce after a garlicky meal can help by neutralizing the sulfur compounds in garlic responsible for its odor.